How Is the AGE Test Performed and How Are Results Interpreted?
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- How Is the AGE Test Performed and How Are Results Interpreted?
This is Part 2 of a two-part series on AGE testing in transformer insulating liquids. In Part 1 we discussed what AGE is and where testing does and does not apply. Here we will discuss the AGE test itself, how results are interpreted, and typical recommendations based on those results.
How the AGE Test Works
The AGE test determines the concentration of the AGE additive present in a perchloroethylene fluid sample. Only a small amount of sample is required — approximately 5 mL.
Test procedure and acid neutralization method
The test is performed by adding a small amount of hydrochloric acid to a measured volume of the perchloroethylene fluid sample and allowing it to sit for a specified period of time. During this interval, any AGE present in the sample reacts with and neutralizes a portion of the acid. After the reaction period, the amount of remaining acid is measured, providing an indication of the AGE concentration in the sample.
Calibration standards and concentration measurement
The sample response is compared against three calibration standards that are run concurrently using the same procedure: a blank, a 1000 ppm AGE standard, and a 2000 ppm AGE standard. The concentration of AGE in the sample is determined by comparing the sample’s response to the responses of these three standards. Results are reported in ppm (parts per million) in a custom letter format, accompanied by recommendations.
AGE Concentration Thresholds and Recommendations
Acceptable, questionable, and unacceptable ranges
SDMyers applies the following guidelines when evaluating AGE concentration results:
- Greater than 1500 ppm AGE is Acceptable (2000–2500 ppm is considered optimum)
- Greater than 1000 ppm but 1500 ppm or less is Questionable
- 1000 ppm or less is Unacceptable
When to replenish vs. when to replace
If AGE content is 1500 ppm or less but greater than 0 ppm, the AGE acid scavenger should be replenished. If AGE content is completely depleted, the transformer should be considered unreliable and should be replaced.
Why Timely Replenishment Matters
If a transformer requires AGE acid scavenger replenishment, it is important that this maintenance be performed promptly in order to prevent irreversible damage to the transformer’s metal components. If AGE is not replenished, acids will eventually form as the fluid breaks down and will attack the metals in the transformer — including brazed joints where the leads exit the windings — making the transformer unreliable.
Summary:
The AGE test quantifies the concentration of allyl glycidyl ether (AGE) acid scavenger remaining in a perchloroethylene retrofill fluid by measuring the fluid’s ability to neutralize a known quantity of hydrochloric acid, calibrated against blank, 1000 ppm, and 2000 ppm standards.
Who should use this test:
- Appropriate for samples from former Askarel-filled transformers retrofilled with perchloroethylene fluid via processes such as System 50
- Not applicable to Wecosol-filled transformers, which used a different proprietary acid scavenger
SDMyers AGE concentration guidelines:
- > 1500 ppm — Acceptable (2000–2500 ppm is optimum)
- > 1000 ppm, ≤ 1500 ppm — Questionable; replenishment required
- ≤ 1000 ppm — Unacceptable; replenishment required
- Completely depleted — Transformer should be considered unreliable and replaced
Key recommendations:
- Transformers filled with perchloroethylene fluid that was never intended to be the final retrofill fluid should be considered unreliable and replaced
- Where AGE remains present but below the acceptable threshold, timely replenishment is critical to preventing irreversible acid attack on metal components, including brazed winding lead joints
